In vitro clonal analysis of rat cerebral cortical neurons expressing latexin, a subtype-specific molecular marker of glutamatergic neurons.

Latexin is expressed in a subset of glutamatergic projection neurons located in the lateral but not the dorsomedial neocortex in rat. In the present study, we performed clonal analysis of embryonic cortical neurons in vitro using latexin as a subtype-specific molecular marker of glutamatergic neurons to address whether certain precursors in early cortical anlage are already committed to a single molecular phenotype. Dissociated cells from lateral cortex at embryonic day 12 were labelled with a replication-deficient retroviral vector containing the bacterial lacZ gene, and cultured in a monolayer for 3 weeks. Double-immunofluorescence staining was used to simultaneously visualize latexin- and beta-galactosidase-immunopositive neurons. Out of 572 beta-galactosidase-immunopositive clones examined, 27 clones contained latexin-expressing neuron(s). Of these 27 clones, 25 clones that contained three or more neurons were mixed clones containing both latexin-immunopositive and -immunonegative neurons. These results suggest that committed precursors to producing solely latexin-expressing neurons are not exist in the early cerebral cortical anlage.